1. Field of the Invention
The present invention relates to ink-jet color recording ink containing microcapsules destroyable with a predetermined stimulus, color ink feeding devices using the ink, and ink-jet color recording apparatus and methods using the ink.
2. Description of the Related Art
Recently, with the spread of computers as information devices whose main ones are personal computers, printers have spread as one of their peripherals. The printers include ones of various types such as, for example, electrophotographic, heat-transfer, and ink-jet recording types. Among others, the full-color printers of the ink-jet recording type have remarkably advanced in which the color images formed thereby tend to match and supersede photographs taken by the conventional silver-salt analog cameras in terms of beautifulness and resolution.
The printers of this ink-jet recording type include ones of the thermal jet type in which the ink droplets are repelled by the force of air bubbles produced by the heaters thereof, and ones of the piezoelectric type in which the ink droplets are repelled by deformation of a piezoelectric element.
In full-color printing, different types of ink with three primary colors: magenta (red), cyan (greenish blue) and yellow, of a subtractive color mixture are usually used. In addition, black ink is used exclusively to print characters and/or black image portions on demand.
Each of these printers ejects ink droplets from an ejection nozzle of its printing head against a recording material such as paper or cloth to cause it to absorb the ink droplets to thereby print characters/images. This printing need not perform a special fixing process. These printers are simple in structure and used as personal ones.
FIG. 24 is a schematic perspective view of a conventional ink-jet printer that performs full-color printing, for example, disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2000-289236.
This printer 101 of FIG. 24 is a small one used personally in a household. A printing head 103 and an ink cartridge 104 that contains ink are attached to a carriage 102.
The carriage 102 is supported slidable on a guide shaft 105 and also fixed to a toothed drive belt 106. Thus, the printing head 103 and the ink cartridge 104 are moved back and forth longitudinally of the printer 101, in the directions of a double-headed arrow C or in a primary scan direction for printing. A flexible communications cable 107 is connected between the printing head 103 and a controller (not shown) of the printer so that print data and control signals are sent from the controller to the printing head 103 through the cable 107.
A platen 109 is disposed at a lower end of a frame 108 of the printer, extending in the primary scan direction of the printing head 103 so as to face the printing head 103. Printing paper P is intermittently conveyed in a secondary print-scan (obliquely lower left) direction of an arrow D by pairs of feed rollers 110 (their lower rollers are behind the printing paper P and not shown) and pairs of discharge rollers 111 (their lower rollers are likewise behind the printing paper and not shown) while the paper is being held between each pair of feed rollers 110 and between each pair of discharge rollers 111.
During a time when the intermittent conveyance of the printing paper P is at a stop, the printing head 103 is driven by a motor 112 through the toothed drive belt 106 and the carriage 102 while ejecting ink droplets against and close to the printing paper to thereby print characters/images. The whole surface of the printing paper P is printed by repeating its intermittent conveyance and reciprocal printing that are performed by the printing head 103 on the printing paper P. The quantity of each type of color ink consumed in printing is newly supplemented from the ink cartridge 104 to the printing head 103.
In one arrangement, the carriage 102 is fixed to the printing head 103 on which the ink cartridge 104 is settable. In another arrangement, a head unit that includes the printing head 103 and the ink cartridge 104 as a unit is fixed removable to the carriage 102.
The printer of FIG. 24 shows that the printing head 103 and the ink cartridge 104 are integral with each other as the head unit.
The ink cartridge 104 of FIG. 24 has three divided chambers 113 that contain porous materials (not shown) impregnated sufficiently with magenta, cyan and yellow ink, respectively, to an extent that they do not flow uselessly away from the ink chambers due to gravity.
These three ink chambers 113 have outlets in the bottoms of the ink chambers 113 that feed the respective types of color ink therethrough to the printing head 103 so that the three types of color ink within the respective ink chambers 113 are fed through ink paths to the corresponding ink-injection nozzle lines in the printing head 103.
FIG. 25 is a schematic perspective view of a conventional full-color ink-jet printer including a separated printing head and ink cartridges.
In the printer 114 of FIG. 25, the printing head 115 is supported by a carriage 116 so as to face a platen roller 117. The carriage 116 is supported slidable by a guide shaft 118 and engaged with a toothed belt 119, which is driven forwardly or backwardly through gears (not shown) by rotating a motor 120 forwardly or backwardly. Thus, the printing head 115 slides along the platen roller 117 longitudinally in the directions of a double headed arrow C (in the primary scan direction) to thereby print characters and/or images on the printing paper P.
The platen roller 117 and auxiliary rollers 121 support the printing paper P therebetween to thereby convey the printing paper P in the direction of arrow D widthwise (in the secondary scan direction) in an intermittent manner to thereby cause the printing head 115 to print in lines sequentially.
Provided removable on the carriage 116 are a black ink cartridge 123 that contains a black ink and a color ink cartridge 124 which has three divided chambers that contain magenta, cyan and yellow color ink, respectively.
FIG. 26A schematically illustrates a main portion of the color printer of the ink-jet recording type. FIG. 26B is a front view of an ink-spitting surface of the printing head (as viewed in the direction of an arrow E in FIG. 26A). While FIGS. 26A and 26B illustrate the use of four different types of colored ink of FIG. 25, this is substantially applicable when three different types of color ink of FIG. 24 are used.
As shown in FIG. 26A, the printing head 7 is disposed close to printing paper P so that the former moves right and left and in the direction perpendicular to the paper face of FIG. 26A relative to the latter.
Provided on the printing head 7 are ink cartridges 8 (8m, 8c, 8y and 8k) that contain four different types of color ink (magenta (M), cyan (C), yellow (Y) and black (K)) through four corresponding ink feed paths 9, for example, of a pipe.
As shown in FIG. 26B, the printing head 7 includes a nozzle array of four different-color nozzle lines 10 on its ink ejection surface with each nozzle line 10 having ejection outlets 11 at a density, for example, of approximately 12 outlets per millimeter. The printing head 7 ejects from the nozzle array different-colored ink droplets fed by the cartridges 8 corresponding to the respective nozzle lines 10 against the printing paper to thereby print characters/images in colors.
As described above, such conventional printer prints images in full color, using three different types of color ink of magenta, cyan and yellow, and/or an additional type of color ink of black. In order to form a good color image using such printer, expression of the image in multigradation is required. In this respect, in the past the multigradation was expressed using area gradation. In order to form a preciser image, using a recent full-color ink-jet printer, however, the use of the area gradation is not satisfactory. In order to express the preciser image in concentration multigradations, a total of 6 or 7 different types of color ink whose colors include the three primary colors; magenta, cyan and yellow, and other derivatives, that is, light magenta, light cyan and dark yellow is often used.
In the ink-jet printer, ink droplets are generally repelled out by the force of bubbles produced by its heaters or by the force produced by deformation of a piezoelectric element used. A so-called acoustic ink-jet printer is also known as another technique, for example, disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2001-301156 in which ultrasonic waves are focused on a point on a free surface of ink to cause ink droplets to be spit out from the free surface of the ink by the energy of the ultrasonic waves.
In contrast to the conventional color-image forming system, a color image forming apparatus of a new type is proposed, for example, in Unexamined Japanese Patent Application KOKAI Publication No.H11-58832 in which external stimulus such as light, heat or ultrasonic waves corresponding to image information are given to dedicated recording paper coated with an ink layer that contains magenta, cyan and yellow microcapsules which respond to the external stimulus to thereby form a color image.
When the conventional ink-jet recording printer prints, however, different amounts of magenta, cyan, yellow and black ink are used depending on the contents of the printing and the corresponding quantities of the ink need be supplemented at the respective different timings. That is, management of the respective color ink cartridges is troublesome.
Especially, in the ink cartridge assembly that includes three different color (magenta, cyan, yellow) ink cartridges formed integrally as a unit (the ink cartridges 104 and 124 of FIGS. 24 and 25, respectively) the whole ink cartridge assembly (104 or 124) need be replaced with another even when only one type of color ink is used up and the other types of color ink remain. Therefore, a big economic load is imposed as a maintenance cost on the user, undesirably.
This also applies to the printers using the above-described 6 or 7 types of color ink. In that case, 6 or 7 different ink cartridges need be prepared always at hand and management of the ink cartridges is more troublesome.
In addition, the printer body has 6 or 7 ink feeders, which renders the structure of the printer complicated and increases the cost of the printer accordingly.
In the color image forming apparatus using the dedicated printing paper coated with the ink layer that contains microcapsules (Unexamined Japanese Patent Application KOKAI Publication No. H11-58832), the whole surface of the recording paper is basically coated with the three different types of color ink, which increases the cost of the printing because some of the types of ink are used wastefully. In addition, in this case general paper cannot be used for printing. Furthermore, the printing process is repeated in different colors, so that a discrepancy in printed color is difficult to control, which renders the printer complicated inevitably.